Component feeding is a well-known process in surface mount technology. In general, a feeder is used to sequentially supply surface mountable electrical components to a pick up location for subsequent placing, by a pick-and-place machine, onto a printed circuit board (PCB) which is pre-printed with solder paste.
Hopper feeders also known as bulk or tube feeders are an alternative to tape and reel feeders. Hopper feeders comprise a hopper in communication, along a downwardly sloping passage, with the pick up location. The downwardly sloping passage makes use of gravity for supplying the components to the pick up location. To further assist the supplying of the components to the pick up location a combination of gravity and air blasting has also been used.
The pick up location has an abutment wall and an aperture. The abutment wall abuts the components supplied from the hopper before they are removed, through the aperture, by the pick-and-place machine. The supply of components to the pick up location must be controlled, otherwise undesirable amounts of friction between the abutment wall and an abutting component can result. This friction is due to a mass of stacked components in the downwardly sloping passage pushing the abutting components into the abutment wall. Accordingly, this friction may cause problems when the pick-and-place machine attempts to remove the abutting component. Further, unnecessary friction between the abutting component and an adjacent component can further hinder the removal of the abutting component.
In order to reduce the friction described above, the supply of components to the pick up location is mechanically controlled to separate components in the downwardly sloping passage from a component in the pick up location. For example, one conventional approach is to use a pneumatically controlled slotted disk located horizontally in series between the pick up location and sloping passage. The slotted disk has two diametrically opposite slots for sequentially engaging a component. The disk rotates through 180 degrees in a timed sequence to thereby transport an individual component, engaged in one of the slots, from the passage to the pick up location.
The above conventional mechanically controlled component separation approach requires valuable limited space. This is primarily due to the disk being substantially larger than the components and for practical reasons it is located horizontally therefore increasing the width of the feeder.
Another method of separating the components is to shape the slope to have an upwardly sloping portion which causes some of the components in the stack of components to slide downwards due to gravity. This separation between the components in the stack reduces the friction between components at the pick up location. However, the friction between a component and the abutment wall, still significantly affects the ability of the pick and place machine to remove the component at the pick up location.